Thermal storage device

ABSTRACT

A thermal storage device having a plurality of tube-like first thermal medium branch pipes ( 5 ) into which a first thermal medium ( 3 ) flows and a thermal storage material ( 1 ) provided on the outer peripheries of the first thermal medium branch pipes ( 5 ) is characterized by including a first header ( 6 ) that communicates with the upper portions of the first thermal medium branch pipes ( 5 ) and allows the first thermal medium ( 3 ) to flow therethrough, a first upper reservoir ( 7 ) that communicates with the first header ( 6 ) and stores the first thermal medium ( 3 ), and a first inlet ( 8 ) that communicates with the first upper reservoir ( 7 ) and allows the first thermal medium ( 3 ) to flow therethrough. The first upper reservoir ( 7 ) is formed in a direction intersecting with the direction of streamline of the first inlet ( 8 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a thermal storage device in which a firstthermal medium and a second thermal medium flow through a thermalstorage material, and more particularly to a thermal storage device thatis able to temporarily store heat (or cool) possessed by a medium, suchas a coolant.

2. Description of the Related Art

Japanese Patent Application Publication No. 2003-336974(JP-A-2003-336974) discloses a thermal-storage device that stores heator cool (thermal heating or thermal cooling) in a thermal storagematerial through contact of the thermal storage material with channelsthrough which a first thermal medium and a second thermal medium flow.In the thermal storage device disclosed in JP-A-2003-336974, a pluralityof first channels and a plurality of second channels are provided, anddirect heat exchange takes place between a heat source fluid and a heatrecovery fluid flowing through the first channels and the secondchannels, respectively. Since the thermal storage material is providedaround the first channels and the second channels, heat of the heatsource fluid is once stored in the thermal storage. material, and thentransmitted to the heat recovery medium for effecting heat exchange.

Japanese Patent Application Publication No. 10-232093 (JP-A-10-232093)discloses a thermal storage device in which heat transfer plates arelaminated or stacked together to form channels through which a firstthermal medium and a second thermal medium are caused to flow, and heatexchange takes place between the first thermal medium and the secondthermal medium within. the thermal storage device. In the thermalstorage device disclosed in JP-A-10-232093, heat is transferred betweenthe first thermal medium and the second thermal medium via the heattransfer plates.

In the thermal storage device disclosed in JP-A-2003-336974 as describedabove, a straight path that extends from an inlet to a tank is provided,and a plurality of channels are formed in a direction that intersectswith the tank. Accordingly, when the amount of flow of the first thermalmedium or second thermal medium introduced through the inlet is varied,the amounts of flow of the first thermal medium or second thermal mediumthat flows in the channels vary depending upon the mounting locations ofthe channels. Therefore, variations arise in the degree of heat transferbetween the first thermal medium or second thermal medium and thethermal storage material, and variations are likely to arise in thetemperature distribution in the thermal storage material.

Also, when the -amount of flow of the first thermal medium or secondthermal medium introduced through the inlet is varied, air bubbles mayappear in the tank or channels, in which a mixture of the bubbles (gas)and the thermal medium (liquid) is created, resulting in a reduction inthe quantity of heat that can be directly transferred between the firstthermal medium and the second thermal medium.

In the thermal storage device disclosed in JP-A-10-232093 as describedabove, the laminated heat transfer plates that effect heat exchangebetween the first thermal medium and the second thermal medium and athermal storage tank that stores heat are separately provided, resultingin an increase in the size of the thermal storage device.

SUMMARY OF THE INVENTION

The invention is concerned with a thermal storage device that uses thesame mechanism for effecting heat exchange between a first thermalmedium and a second thermal medium and storing heat in a thermal storagematerial. It is an object of the invention to provide such a thermalstorage device that is less likely to suffer from variations in theamount of flow of the first thermal medium or second thermal mediumthrough a plurality of channels, depending upon the mounting locationsof the channels, even when the amount of the first thermal medium orsecond thermal medium introduced into the device is varied. It is alsoan object of the invention to provide a thermal storage device in whichtubes through which a thermal medium flows are provided in blades,assuring improved overall rigidity.

According to a first aspect of the invention, there is provided athermal storage device including a plurality of tube-like first thermalmedium branch pipes into which a first thermal medium flows, a thermalstorage material provided on the outer peripheries of the first thermalmedium branch pipes, a first header that communicates with upperportions of the first thermal medium branch pipes and allows the firstthermal medium to flow therethrough, a first upper reservoir thatcommunicates with the first header and stores the first thermal medium,and a first inlet that communicates with the first upper reservoir andallows the first thermal medium to flow therethrough, wherein the firstupper reservoir is formed in a direction intersecting with a directionof streamline of the first inlet.

In the thermal storage device according to the above aspect of theinvention, the upper reservoir may have a bottom face that is inclinedupwards from a lower portion of the upper reservoir.

In the thermal storage device according to the above aspect of theinvention, a cross-sectional area of the upper reservoir when cut in adirection parallel to a lower face of the first header may be smaller ina lower portion of the upper reservoir than in an upper portion thereof,and the cross-sectional area may increase from the lower portion towardthe upper portion.

The thermal storage device according to the above aspect of theinvention may further include a plurality of second thermal mediumbranch pipes through which a second thermal medium flows, a secondheader that communicates with upper portions of the second thermalmedium branch pipes and allows the second thermal medium to flowtherethrough, a second upper reservoir that communicates with the secondheader, and stores the second thermal medium, and a second outlet thatcommunicates with the second upper reservoir and allows the secondthermal medium to flow therethrough. In this device, the thermal storagematerial may be provided on the outer peripheries of the second thermalmedium branch pipes, and the second upper reservoir may be formed in adirection intersecting with a direction of streamline of the secondoutlet, while the first upper reservoir and the second upper reservoirmay be in contact with each other.

In the thermal storage device according to the above aspect of theinvention, the first header and the second header may be in contact witheach other.

The thermal storage device according to the above aspect of theinvention may further include a plurality of first plate-like tubes thatare arranged in parallel with each other to extend in a verticaldirection of the thermal storage device. In this device, the firstthermal medium branch pipes may be disposed in the vertical direction ofthe first plate-like tubes.

The thermal storage device according to the above aspect of theinvention may further include a plurality of second plate-like tubesthat are arranged in parallel with each other to extend in a verticaldirection of the thermal storage device. In this device, the secondthermal medium branch pipes may be disposed in a vertical direction ofthe second plate-like tubes.

The thermal storage device as described just above may further include aplurality of first plate-like tubes that are arranged in parallel witheach other to extend in the vertical direction of the thermal storagedevice. In this device, the first thermal medium branch pipes may bedisposed in a vertical direction of the first plate-like tubes, and thefirst plate-like tubes and the second plate-like tubes may be arrangedin parallel with each other so as to be perpendicular to aninlet/outlet-side side face of the thermal storage device in which thefirst inlet and the second outlet are provided.

Each of the first plate-like tubes and the second plate-like tubes maybe formed by joining two heat transfer plates to each other, and thefirst thermal medium branch pipes and the second thermal medium branchpipes may be inserted through grooves formed in mating faces of the twoheat transfer plates.

The first plate-like tubes may extend through at least one of the secondupper reservoir and a second lower reservoir, and at least one hole maybe formed in the first plate-like tubes.

The second plate-like tubes may extend through at least one of thesecond upper reservoir and a second lower reservoir, and at least onehole may be formed in the second plate-like tubes.

In the thermal storage device according to the above aspect of theinvention, the first thermal medium may be brine, and the second thermalmedium may be a coolant.

According to a second aspect of the invention, there is provided acirculation system including the thermal storage device according to thefirst aspect of the invention, and a heat exchanger, wherein the firstthermal medium circulates between the thermal storage device and theheat exchanger.

The circulation system according to the above aspect of the inventionmay further include a compressor, a condenser, a receiver tank and anexpansion valve. In this system, the second thermal medium may circulatebetween the thermal storage device and the. compressor, and thecondenser, the receiver tank and the expansion valve may be connected inthe order of description between the compressor and the thermal storagedevice.

According to the first aspect of the invention, when the first thermalmedium flows into the thermal storage device through the first inlet,the first thermal medium is stored in the first upper reservoir, andthen flows from the first upper reservoir into the first header. Since achange in the amount of flow of the first thermal medium introducedthrough the first inlet is transmitted to the first header via the firstupper reservoir, a change in the amount of flow of the first thermalmedium in the first header is made smaller than the change in the amountof flow of the first thermal medium through the first inlet.Consequently, the amount of flow of the first thermal medium through thefirst thermal medium branch pipes is more stabilized, and variations inthe temperature distribution in the thermal storage material in responseto changes in the amount of flow of the first thermal medium arereduced.

With the arrangement in which the upper reservoir is formed with aninclined bottom face, pressure losses are reduced when the first thermalmedium flows from the first inlet into the thermal storage device, andcirculates in the interior of the thermal storage device.

In the embodiment having the second thermal medium branch pipes, thesecond thermal medium flows through the second thermal medium branchpipes and the second header, and is stored in the second upperreservoir. Since the first upper reservoir and the second upperreservoir are in contact with each other, direct heat exchange can beeffected between the first thermal medium stored in the first upperreservoir and the second thermal medium stored in the. second upperreservoir even if no thermal energy is stored in the thermal storagematerial.

Also, when the first thermal medium is stored in the first header, andthe second thermal medium is stored in the second header, direct heatexchange can be effected between the first thermal medium and the secondthermal medium even if no thermal energy is stored in the thermalstorage material.

In the arrangement where the first plate-like tubes are provided, thethermal storage device can be constructed by a simple means as apressure-resistant structure that is resistant to pressure applied in adirection parallel to the planes of the first plate-like tubes. Thus,the size, weight and cost of the thermal storage device can be reduced.

In the arrangement where the second plate-like tubes are provided, thethermal storage device can be constructed by a simple means as apressure-resistant structure that is resistant to pressure applied in adirection parallel to the planes of the second plate-like tubes. Thus,the size, weight and cost of the thermal storage device can be reduced.

In the arrangement where holes are formed in the first plate-like tubesthat extend through the reservoir(s), a total cross-sectional area ofchannels in the reservoir through which the first plate-like tubesextend can be expanded or increased, resulting in a reduction inpressure loss of the first thermal medium or second thermal medium.

In the arrangement where holes are formed in the second plate-like tubesthat extend through the reservoir(s), a total cross-sectional area ofchannels in the reservoir through which the second plate-like tubesextend can be expanded or increased, resulting in a reduction inpressure loss of the first thermal medium or second thermal medium.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and further objects, features and advantages of theinvention will become apparent from the following description ofpreferred embodiments with reference to the accompanying drawings,wherein like numerals are used to represent like elements, and wherein:

FIG. 1 is a view schematically showing a thermal storage deviceaccording to a first embodiment of the invention;

FIG. 2 is a perspective view showing the outward appearance of thethermal storage device of FIG. 1;

FIG. 3 is a view schematically showing a circulation path of a firstthermal medium;

FIG. 4 is a view schematically showing a circulation path of a secondthermal medium;

FIG. 5 is a view schematically showing a thermal storage device providedwith plate-like tubes according to a second embodiment of the invention;

FIG. 6 is an enlarged, lateral cross-sectional view showing principalparts of the plate-like tubes used in the thermal storage device of FIG.5; and

FIG. 7 is a view schematically showing a modified example of the thermalstorage device of FIG. 5 in which holes are formed in the plate-liketubes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be described in more detail. The thermal storagedevice of this invention is able to store both positive heat thatincreases energy and negative heat that reduces the energy. In thefollowing description, specific examples will be illustrated which arearranged to store “cool” or thermal cooling for reduction of the energy.

Referring to FIG. 1 and FIG. 2, a thermal storage device 4 according toa first embodiment of the invention will be described. FIG. 2 is aperspective view of the thermal storage device 4 of this embodiment. Asseen in FIG. 2, the thermal storage device 4 is in the form of a prismhaving a quadrangular bottom face. FIG. 1 is a view schematicallyshowing the interior of the thermal storage device 4. As shown in FIG.1, a coolant as a second thermal medium 2 introduces cool or thermalcooling into a thermal storage material 1, and brine as a first thermalmedium 3 delivers or discharges the cool stored in the thermal storagematerial 1 out of the material 1. Thus, the thermal storage device 4 isconstructed as a cool storage device that stores negative heat thatreduces energy.

The thermal storage device 4 includes the thermal storage material 1, aplurality of first thermal medium branch pipes 5 that are insertedthrough the thermal storage material 1 and allow the first thermalmedium 3 to flow therethrough, and a first header 6 that is located inthe upper part of the thermal storage device 4 and defines a hollow inthe interior thereof More specifically, the first thermal medium branchpipes 5 have respective hollows or bores formed in the inside thereof soas to allow the first thermal medium 3 to flow therethrough, and arearranged to extend in the vertical direction (perpendicular to thebottom face of the thermal storage device 4) within the thermal storagedevice 4. The thermal storage material 1 is formed so as to surround theouter peripheries of the first thermal medium branch pipes 5. The lowerface of the first header 6 is formed in parallel with the bottom face ofthe thermal storage device 4, and the first thermal medium branch pipes5 are evenly arranged over the lower face of the first header 6. Withthis arrangement, when the first thermal medium 3 in the form of brinefor discharging cool is evenly passed through the respective firstthermal medium branch pipes 5, the cool stored in the thermal storagematerial 1 is delivered evenly out of the material 1 in the thermalstorage device 4. Since the thermal storage material 1 is in contactwith the outer peripheries of the first thermal medium branch pipes 5,heat exchange or thermal energy exchange takes place between the firstthermal medium 3 flowing through the first thermal medium branch pipes 5and the thermal storage medium 1.

In the thermal storage device 4, the upper parts of the first thermalmedium branch pipes 5 communicate with the first header 6. Morespecifically, the first header 6 has a hollows formed in the interiorthereof, and is disposed in the upper portion of the thermal storagedevice 4 such that the lower face of the first header 6 is in parallelwith the bottom face of the thermal storage device 4. Thus, the firstthermal medium 3 is caused to flow substantially uniformly within thefirst header 6. Furthermore, the areas of the upper and lower faces ofthe first header 6 are made as large as possible. While the upper endsof the first thermal medium branch pipes 5 protrude upwards into theinterior of the first header 6 in the example shown in FIG. 1, the upperends of the first thermal medium branch pipes 5 may or may not protrudeinto the first header 6 as long as the first thermal medium 3 can flowbetween the first header 6 and the first thermal medium branch pipes 5.The first thermal medium branch pipes 5 and the first header 6 arejoined to each other by, for example, welding.

The thermal storage device 4 is also provided with a first upperreservoir 7 that stores the first thermal medium 3. The first upperreservoir 7 is a hollow formed in the upper part of one side portion ofthe thermal storage device 4, and communicates with the first header 6.The thermal storage device 4 is further provided with a tube-like firstinlet 8 through which the first thermal medium 3 flows into the firstupper reservoir 7. The first upper reservoir 7 extends in a directionintersecting with the direction of streamline of the first inlet 8,toward the top of the thermal storage device 4. The area of across-section of the first upper reservoir 7 taken along the directionof streamline of the first inlet 8 is made as large as possible. As thiscross-sectional area of the first upper reservoir 7 increases, theamount of a rise in the liquid level of the first thermal medium 3flowing from the first inlet 8 is reduced in the first upper reservoir7. The amount of the rise is based on the ratio between thecross-sectional area of the first inlet 8 when taken in a planeorthogonal to the direction of streamline and the above-indicatedcross-sectional area of the first upper reservoir 7. If thecross-sectional area of the first inlet 8 is small, or thecross-sectional area of the first upper reservoir 7 is large, the amountof the rise in the liquid level of the first thermal medium 3 in thefirst upper reservoir 7 is reduced.

The first upper reservoir 7 has a hollow formed therein, and the firstthermal medium 3 is stored in the first upper reservoir 7. The firstinlet 8 is attached to one outside surface of the first upper reservoir7, namely, to one side (or wall) of the thermal storage device 4 onwhich the first upper reservoir 7 is formed. The first upper reservoir 7communicates with the first header 6 at a location above the face of thefirst upper reservoir 7 opposed to the face to which the first inlet 8is attached. It is desirable that the first upper reservoir 7 isperpendicular to the lower face of the first header 6. However, thefirst reservoir 7 may be inclined downwards relative to the lower faceof the first header 6, such that the first thermal medium 3 can bestored in the first reservoir 7. The first header 6 is provided abovethe lower face of the first upper reservoir 7.

The first inlet 8 is shaped-like a tube, and its one end communicateswith the first upper reservoir 7. More specifically, the first inlet 8communicates with a lower portion of the first upper reservoir 7, and isprovided below the lower face of the first header 6. While it isdesirable that the first upper reservoir 7 is formed in a directionperpendicular to the direction of streamline of the first inlet 8, thefirst upper reservoir 7 may be inclined and extend upwards relative tothe direction of streamline of the first inlet 8. With this arrangement,when the first thermal medium 3 flows into the first upper reservoir 7through the first inlet 8, pulsation of the first thermal medium 3,which would occur when the amount of the introduced first thermal medium3 increases or decreases, is absorbed in the first upper reservoir 7.

The thermal storage device 4 is further provided with a first footer 9that communicates with the lower end portions of the first thermalmedium branch pipes 5. More specifically, the first footer 9 is providedin the lower part of the thermal storage device 4 such that a hollow isformed in the interior of the first footer 9, and such that the lowerface of the first footer 9 is parallel with the bottom face of thethermal storage device 4. With this arrangement, the first thermalmedium 3 is stored in the first footer 9. Here, the areas of the upperand lower faces of the first footer 9 are made as large as possible.

Since the first footer 9 communicates at its upper face with the firstthermal medium branch pipes 5, and the first thermal medium branch pipes5 are evenly arranged over the upper face of the first footer 9 withinthe thermal storage device 4, the stored cool can be uniformly deliveredout of the thermal storage material 1 in the thermal storage device 4via the first thermal medium 3 flowing through the first thermal mediumbranch pipes 5. The lower end portions of the first thermal mediumbranch pipes 5 may or may not protrude downwards into the first footer 9as long as the first thermal medium 3 can flow between the first thermalmedium branch pipes 5 and the first footer 9. The first thermal mediumbranch pipes 5 and the first footer 9 are joined to each other by, forexample, welding.

The thermal storage device 4 is also provided with a first lowerreservoir 10 that communicates with the first footer 9, and a firstoutlet 11 that communicates with the first lower reservoir 10. Morespecifically, the first lower reservoir 10 is a hollow formed in a lowerpart of the above-indicated one side portion of the thermal storagedevice 4 in which the first upper reservoir 7 is formed. The firstoutlet 11 is attached to one outside surface of the first lowerreservoir 10, namely, to a side wall of the thermal storage device 4which partially defines the first upper reservoir 7 and the first lowerreservoir 10. The first lower reservoir 10 communicates with the firstfooter 9 at a location below the face of the first lower reservoir 10opposed to the face to which the first outlet 11 is attached. While itis desirable that the first lower reservoir 10 is perpendicular to thelower face of the first footer 9, the first lower reservoir 10 may beinclined upwards relative to the lower face of the first footer 9. Withthis arrangement, the first thermal medium 3 can be stored in the firstlower reservoir 10. The first footer 9 is provided below the upper faceof the first lower reservoir 10.

The first outlet 11 is shaped like a tube, and communicates at one endthereof with the first lower reservoir 10. In this thermal storagedevice 4, it is desirable that the first lower reservoir 10 is formed ina direction perpendicular to the direction of streamline of the firstoutlet 11. However, the first lower reservoir 10 may not necessarily beformed in this direction, but may be inclined and extends downwardsrelative to the direction of streamline of the first outlet 11.

As shown in FIG. 2, an inclined face 12 is formed within the first upperreservoir 7, such that the inclined face 12 extends from a lower portionof the first upper reservoir 7 to an upper portion thereof. The inclinedface 12 is provided by a slope that is formed in the bottom face of thefirst upper reservoir 7 so as to extend from the vicinity of a point atwhich the first inlet 8 is attached, toward the top of the thermalstorage device 4, along the side face to which the first inlet 8 isattached. In other words, the area of a cross-section of the first upperreservoir 7 taken in a direction parallel to the lower face of the firstheader 6 is relatively small on the lower side of the reservoir 7, andincreases toward the upper side thereof. Accordingly, as the amount ofstorage of the first thermal medium 3 introduced from the first inlet 8increases, the amount of a rise in the liquid level of the first thermalmedium 3 in the first upper reservoir 7 is reduced. Thus, a change inthe amount of flow of the first thermal medium 3 fed from the firstinlet is reduced when the medium 3 flows into the first header 6. Also,the provision of the inclined face 12 makes it possible to reduce a loss(pressure loss) encountered when the liquid level of the first thermalmedium 3 introduced from the first inlet 8 rises in the first upperreservoir 7.

Next, passages through which the second thermal medium 2 in the form ofa coolant circulates will be explained. The thermal storage device 4 isprovided with a plurality of second thermal medium branch pipes 13through which the second thermal medium 2 flows, such that the branchpipes 13 are inserted through the thermal storage material 1, and suchthat the outer peripheries of the branch pipes 13 are surrounded by thethermal storage material 1. More specifically, the plurality of secondthermal medium branch pipes 13 are arranged to extend in directionsperpendicular to the bottom face of the thermal storage device 4 so asto allow the second thermal medium 2 to flow in the vertical directionof the thermal storage device 4. Since the thermal storage material 1 isin contact with the outer peripheries of the second thermal mediumbranch pipes 13, heat (or thermal energy) exchange takes place betweenthe thermal storage material 1 and the second thermal medium 2 flowingthough the second thermal medium branch pipes 13.

The thermal storage device 4 is also provided with a second header 14that communicates with the upper portions of the second thermal mediumbranch pipes 13 and allows the second thermal medium to flowtherethrough. More specifically, the second header 14 has a hollowformed therein, and the second thermal medium 2 is stored in the secondheader 14. The second header 14 that communicates with the upperportions of the second thermal medium branch pipes 13 is provided in theupper portion of the thermal storage device 4, such that the lower faceof the second header 14 is in parallel with the lower face of thethermal storage device 4. Thus, the second thermal medium 2 flowssubstantially uniformly in the second header 14.

The second thermal medium branch pipes 13 communicate with the secondheader 14. While the upper ends of the second thermal medium branchpipes 13 protrude upwards into the second header 14 in the example shownin FIG. 1, the upper ends of the second thermal medium branch pipes 13may not protrude into the second header 14 as long as the second thermalmedium 2 can flow between the second header 14 and the second thermalmedium branch pipes 13. The second header 14 and the second thermalmedium branch pipes 13 are joined to each other by, for example,welding. Where the second header 14 is disposed under the first header6, the first thermal medium branch pipes 5 extend through the secondheader 14 and communicate with the first header 6.

Here, the first header 6 and the second header 14 are in contact witheach other in the upper portion of the. thermal storage device 4. Morespecifically, the second header 14 is disposed under the first header 6,and the lower face of the first header 6 and the upper face of thesecond header 14 are in contact with each other. With this arrangement,heat (or thermal energy) exchange takes place between the first thermalmedium 3 stored in the first header 6 and the second thermal medium 2stored in the second header 14.

The thermal storage device 4 is further provided with a second upperreservoir 15 that communicates with the second header 14 and stores thesecond thermal medium, and a second outlet 16 that communicates with thesecond upper reservoir 15 and allows the second thermal medium to flowtherethrough. The second upper reservoir 15 extends upwards in adirection intersecting with the direction of streamline of the secondoutlet 16. More specifically, the second upper reservoir 15 has a hollowformed therein, and the second thermal medium 2 is stored in the secondupper reservoir 15.

The second upper reservoir 15 communicates with the second header 6 at alocation above the face of the second upper reservoir 15 to which thesecond outlet 16 is not attached, namely, the face opposed to the faceto which the second outlet 16 is attached. While it is desirable thatthe second upper reservoir 15 is perpendicular to the lower face of thesecond header 14, the second upper reservoir 15 may be inclineddownwards relative to the lower face of the second header 14. The secondheader 14 is provided above the lower face of the second upper reservoir15.

In the thermal storage device 4, the first upper reservoir 7 and thesecond upper reservoir 15 are arranged to be in contact with each other.More specifically, the second upper reservoir 15 is provided inside thefirst upper reservoir 7, and the inner side face of the first upperreservoir 7 and the outer side face of the second upper reservoir 15 arein contact with each other. In other words, the side face of the firstupper reservoir 7 closer to the first header 6 and the side face of thesecond upper reservoir 15 remote from the second header 14 are incontact with each other. With this arrangement, heat exchange takesplace between the first thermal medium 3 stored in the first upperreservoir 7 and the second thermal medium 2 stored in the second upperreservoir 15.

The second outlet 16 is shaped like a tube, and is provided at the lowerside of the second upper reservoir 15 such that one end of the secondoutlet 16 communicates with the second upper reservoir 15. While it isdesirable that the second upper reservoir 15 extends in a directionperpendicular to the direction of streamline of the second outlet 16,the second upper reservoir 15 may be inclined and extend upwardsrelative to the direction of streamline of the second outlet 16.

The thermal storage device 4 is further provided with a second footer 17that communicates with the lower portions of the second thermal mediumbranch pipes 13. More specifically, the second footer 17 is provided ina lower portion of the thermal storage device 4, such that a hollow isformed in the interior of the second footer 17 and the lower face of thesecond footer 17 is in parallel with the bottom face of the thermalstorage device 4. Thus, the second thermal medium 2 flows into thesecond footer 17.

The upper face of the second footer 17 is given a large area, and thesecond thermal medium branch pipes 13 are evenly arranged over the upperface of the second footer 17, so that thermal energy of the coolant isevenly or uniformly stored in the interior of the thermal storage device4. Thus, the second thermal medium 2 flows substantially uniformly inthe second footer 17. The lower end portions of the second thermalmedium branch pipes 13 may or may not protrude downwards into the secondfooter 17 as long as the second thermal medium 2 can flow between thesecond thermal medium branch pipes 13 and the second footer 17 thatcommunicate with each other.

The second footer 17 and the second thermal medium branch pipes 13 arejoined to each other by, for example, welding. In the presentembodiment, the second footer 17 is disposed above the first footer 9.In this case, the first thermal medium branch pipes 5 extend through thesecond footer 17, and communicate with the first footer 9.

The thermal storage device 4 is also provided with a second lowerreservoir 18 that communicates with the second footer 17, and a secondinlet 19 that communicates with the second lower reservoir 18. Thesecond lower reservoir 18 has a hollow formed therein, and the secondinlet 19 communicates with the upper portion of the second lowerreservoir 18. The second lower reservoir 18 communicates with the secondfooter 17 at an end portion of the second lower reservoir 18 on the sidewhere the second inlet 19 is not attached, in other words, at a locationbelow the face of the second lower reservoir 18 opposed to the face towhich the second inlet 19 is attached. While it is desirable that thesecond lower reservoir 18 is perpendicular to the lower face of thesecond footer 17, the second lower reservoir 18 may be inclined upwardsrelative to the lower face of the second footer 17.

The second inlet 19 is shaped like a tube, and communicates at one endthereof with the second lower reservoir 18. In the thermal storagedevice 4, the second lower reservoir 18 is formed in a directionintersecting with the direction of streamline of the second inlet 19.While it is desirable that the second lower reservoir 18 is formed in adirection perpendicular to the direction of streamline of the secondinlet 19, the invention is not limited to this arrangement, but thesecond lower reservoir 18 may be inclined and extend downwards relativeto the direction of streamline of the second inlet 19.

In the thermal storage device 4, the first thermal medium branch pipes 5and the second thermal medium branch pipes 13 are arranged in parallelwith each other, and the thermal storage material 1 is provided betweenthe first thermal medium branch pipes 5 and the second thermal mediumbranch pipes 13. Therefore, cool is transmitted from the second thermalmedium 2 flowing through the second thermal medium branch pipes 13 tothe thermal storage material 1, and is stored in the thermal storagematerial 1. At this time, the thermal storage material 1 takes cool outof the second thermal medium 2, and the state of the second thermalmedium 2 changes from a liquid state to a gaseous or vapor state. Also,the cool stored in the thermal storage material 1 is transmitted to thefirst thermal medium 3 flowing through the first thermal medium branchpipes 5.

The first thermal medium branch pipes 5 and the second thermal mediumbranch pipes 13 may contact with each other within the thermal storagedevice 4. In this case, direct heat (or thermal energy) exchange takesplace between the first thermal medium 3 flowing through the firstthermal medium branch pipes 5 and the second thermal medium 2 flowingthrough the second thermal medium branch pipes 13, at portions where thefirst thermal medium branch pipes 5 contact with the second thermalmedium branch pipes 13.

FIG. 3 is a schematic view illustrating a circulation system throughwhich the first thermal medium 3 in the form of brine circulates. A flowpassage through which the first thermal medium 3 flows within thethermal storage device 4 forms a part of a circulation path throughwhich the first thermal medium 3 circulates between the thermal storagedevice 4 and a heat exchanger 24, such as a heat exchanger installed onthe vehicle-compartment side. A pump 25 is interposed between thethermal storage device 4 and the heat exchanger 24 in the circulationpath. The flow passage specifically refers to a passage that extendsfrom the first inlet 8 to the first outlet 11 via the first upperreservoir 7, first header 6, each of the first thermal medium branchpipes 5, first footer 9, and the first lower reservoir 10.

FIG. 4 is a schematic view illustrating a circulation system throughwhich the second thermal medium 2 in the form of a coolant circulates.The circulation system includes a compressor 20 driven by a power source(not shown), such as an engine of the vehicle, and a condenser 21, areceiver tank 22 and an expansion valve 23 which are connected in thisorder to the discharge side of the compressor 20. The second inlet 19 isconnected to the discharge side of the expansion valve 23, and thesecond outlet 16 that is not connected to the discharge side of theexpansion valve 23 is connected to the inlet side of the compressor 20.

FIG. 5 illustrates a thermal storage device 24 according to a secondembodiment of the invention, in which the first thermal medium 3 in theform of brine delivers cool or thermal cooling out of the thermalstorage material 1, and the second thermal medium 2 in the form of acoolant introduces cool into the thermal storage material 1, as in thethermal storage device 4 of FIG. 1. In the thermal storage device 24, aplurality of plate-like tubes are arranged to extend in a direction(vertical direction) substantially perpendicular to the bottom face ofthe thermal storage device 24, and the thermal storage material 1 isprovided between the plate-like tubes. The first thermal medium branchpipes 5 and the second thermal medium branch pipes 13 extend along thevertical direction of the plate-like tubes. In FIG. 5, the samereference numerals as used in FIG. 1 are used for identifying the sameor corresponding constituent elements as those of the thermal storagedevice 4 as shown in FIG. 1, and explanation of these elements not heprovided.

In the thermal storage device 24, the first thermal medium branch pipes5 are formed in the vertical direction of first plate-like tubes 26, andthe second thermal medium branch pipes 13 are formed in the verticaldirection of second plate-like tubes 27. As shown in FIG. 6, each of thefirst plate-like tubes 26 and the second plate-like tubes 27 isfabricated by joining mutually opposed, two heat transfer plates 28, 29to each other. Each of the heat transfer plates 28, 29 have elongatedprojections 28A, 29A that are formed by bending at certain intervals insubstantially parallel with the vertical direction, and a hollow isformed inside each elongated projection 28A, 29A. Each of the heattransfer plates 28, 29 also includes flat portions 28B, 29B locatedbetween the corresponding elongated projections 28A, 29A. Each of theelongated projections 28A, 29A may have any desired cross-sectionalshape, such as a triangle, a quadrangle, or a semicircle. In the exampleof FIG. 6, the cross-sectional shape of each elongated projection 28A,29A is a triangle whose bottom is provided by the corresponding flatportion 29B, 28B of the heat transfer plate 29, 28 that is opposed tothe heat transfer plate 28, 29 having the elongated projection 28A, 29A.Namely, the hollow formed in each of the elongated projections 28A, 29Ais open to the mating faces of the corresponding heat transfer plates28, 29. Since the heat transfer plates 28, 29 are joined to each othersuch that the elongated projections 28A, 29A of one of the heat transferplates 28, 29 are opposed to the flat portions 29B, 28B of the otherheat transfer plate 29, 28, the hollows formed in the elongatedprojections 28A, 29A of the above-indicated one heat transfer plate 28,29 are respectively closed by the flat portions 29B, 28B of the otherheat transfer plate 29, 28. The hollows thus formed provide grooves thatextend in the vertical direction of the thermal storage device 24. Thefirst thermal medium branch pipes 5 and the second thermal medium branchpipes 13 are disposed in the grooves thus formed inside the respectiveelongated projections 28A, 29A.

As shown in FIG. 5, the first plate-like tubes 26 and the secondplate-like tubes 27 are arranged in parallel with each other, to extendin a direction substantially perpendicular to the bottom face of thethermal storage device 24, and in a direction perpendicular to a sideface (which will be referred to as “inlet/outlet-side side face”) of thethermal storage device 24 which is provided with the first inlet 8,second inlet 19, first outlet 11 and the second outlet 16. The firstplate-like tubes 26 extend through the lower face of the first header 9and the upper face of the first footer 9. When viewed from above thethermal storage device 24, the upper end portions of the firstplate-like tubes 26 that extend through the lower face of the firstheader 6 are oriented so as to be in parallel with the direction of theflow path of the first thermal medium 3 that flows in the first header6. Thus, the thermal storage device 24 incorporating the firstplate-like tubes 26 provides a pressure-resistant structure that isresistant to pressures in the vertical direction and the direction ofthe flow path of the first thermal medium 3 flowing in the first header6. The direction of the flow path of the first thermal medium 3 flowingin the first header 6 refers to a direction of stream-like flow from theinlet/outlet-side side face of the thermal storage device 24 toward theopposite side face.

The first plate-like tubes 26 may extend through at least one of thesecond upper reservoir 15 and the second lower reservoir 18. Morespecifically, since the planes of the first plate-like tubes 26 areperpendicular to the bottom face of the thermal storage device 24 andare perpendicular to the inlet/outlet-side side face, the firstplate-like tubes 26 extend through at least one of the second upperreservoir 15 and the second lower reservoir 18 in a directionsubstantially perpendicular to the bottom face of the thermal storagedevice 24 and perpendicular to the inlet/outlet-side side face. Thereservoirs and the first plate-like tubes 26 are joined to each otherby, for example, welding.

Where the second header 14 is disposed under the first header 6, thefirst plate-like tubes 26 extend through the second header 14 as well asthe lower face of the first header 6. Furthermore, where the secondfooter 17 is disposed above the first footer 9, the first plate-liketubes 26 extend through the second footer 17 as well as the upper faceof the first footer 9.

FIG. 7 shows a modified example of the thermal storage device 24 inwhich a plurality of holes 30 are formed in a part of the firstplate-like tubes 26 that extend through at least one of the reservoirs.As described above, the first plate-like tubes 26 extend through atleast one of the second upper reservoir 15 and the second lowerreservoir 18, in the direction perpendicular to the bottom face of thethermal storage device 24 and perpendicular to the inlet/outlet-sideside face. With the plurality of holes 30 thus provided, the secondthermal medium stored in the reservoir(s) can move in the reservoir(s).The holes 30 may have a circular, triangular, rectangular, or any othershape, provided that the second thermal medium stored in thereservoir(s) can flow through the holes 30. Since the first plate-liketubes 26 extend through the reservoirs, the thermal storage device 24provides a pressure-resistant structure that is resistant to pressuresin the vertical direction and the direction of the flow path of thefirst thermal medium 3 flowing in the first header 6.

Also, the second plate-like tubes 27 extend through the lower face ofthe second header 14 and the upper face of the second footer 17. Whenviewed from above the thermal storage device 24, the upper end portionsof the second plate-like tubes 27 that extend through the lower face ofthe second header 14 are oriented so as to be in parallel with thedirection of the flow path of the second thermal medium 2 flowing in thesecond header 14. Thus, the thermal storage device 24 incorporating thesecond plate-like tubes 26 provides a pressure-resistant structure thatis resistant to pressures in the vertical direction and the direction ofthe flow path of the second thermal medium 2 flowing in the secondheader 14. The direction of the flow path of the second thermal medium 2flowing in the second header 14 refers to a direction of stream-likeflow from the inlet/outlet-side side face of the thermal storage device24 toward the opposite side face.

The second plate-like tubes 27 may extend through at least one of thesecond upper reservoir 15 and the second lower reservoir 18. Morespecifically, since the planes of the second plate-like tubes 27 areperpendicular to the bottom face and inlet/outlet-side side face of thethermal storage device 24, the second plate-like tubes 27 extend throughat least one of the second upper reservoir 15 and the second lowerreservoir 18 in the direction perpendicular to the bottom face andinlet/outlet-side side face of the thermal storage device 24. Thereservoirs and the second plate-like tubes 27 are joined to each otherby, for example, welding.

The second plate-like tubes 27 that extend through at least one of thereservoirs is provided with a plurality of holes 30. The holes 30 mayhave a circular, triangular, rectangular, or any other shape, providedthat the second thermal medium 2 stored in the reservoir(s) can flowthrough the holes 30. Since the second plate-like tubes 27 extendthrough the reservoir(s), the thermal storage device 24 provides apressure-resistant structure that is resistant to pressures in thevertical direction and the direction of the flow path of the secondthermal medium 2 that flows in the second header 14.

In the embodiments described above, carbon dioxide may be used as acoolant, which may serve as the second thermal medium 2, for example,and sodium chloride fluid can be used as brine, which may serve as thefirst thermal medium 3, for example.

In the embodiments described above, the thermal storage device being inthe form of a prism having a quadrangular bottom face is explained withan example. However the thermal storage device of the invention is notlimited to such form. For example, the thermal storage device may beformed in a cylindrical shape.

While the invention has been described with reference to the exemplaryembodiments thereof, it is to be understood that the invention is notlimited to the exemplary embodiments and constructions. To the contrary,the invention is intended to cover various modifications and equivalentarrangements.

In addition, while the various elements of the exemplary embodiments areshown in various combinations and configurations, which are exemplary,other combinations and configurations, including more, less or only asingle element, are also within the scope of the invention.

1. A thermal storage device comprising: a plurality of tube-like firstthermal medium branch pipes into which a first thermal medium flows; athermal storage material provided on the outer peripheries of the firstthermal medium branch pipes; a first header that communicates with upperportions of the first thermal medium branch pipes and allows the firstthermal medium to flow therethrough; a first upper reservoir thatcommunicates with the first header and stores the first thermal medium;and a first inlet that communicates with the first upper reservoir andallows the first thermal medium to flow therethrough, wherein the firstupper reservoir is formed in a direction intersecting with a directionof streamline of the first inlet, the first header is provided above alower face of the first upper reservoir, and the first upper reservoiris perpendicular to or inclined downwards relative to a lower face ofthe first header.
 2. A thermal storage device comprising: a plurality oftube-like first thermal medium branch pipes into which a first thermalmedium flows; a thermal storage material provided on the outerperipheries of the first thermal medium branch pipes; a first headerthat communicates with upper portions of the first thermal medium branchpipes and allows the first thermal medium to flow therethrough; a firstupper reservoir that communicates with the first header and stores thefirst thermal medium; and a first inlet that communicates with the firstupper reservoir and allows the first thermal medium to flowtherethrough, the first upper reservoir is formed in the upper part ofthe thermal storage device and in a direction intersecting with adirection of streamline of the first inlet, and the first header isdisposed in the upper part of the thermal storage device above a lowerface of the first upper reservoir and the first upper reservoir islocated in one side portion of the thermal storage device.
 3. Thethermal storage device according to claim 1, wherein the first upperreservoir has a bottom face that is inclined upwards from a lowerportion of the upper reservoir.
 4. The thermal storage device accordingto claim 3, wherein a cross-sectional area of the first upper reservoirwhen cut in a direction parallel to a lower face of the first header issmaller in a lower portion of the first upper reservoir than in an upperportion thereof, and the cross-sectional area increases from the lowerportion toward the upper portion.
 5. The thermal storage deviceaccording to claim 1, further comprising: a plurality of second thermalmedium branch pipes through which a second thermal medium flows; asecond header that communicates with upper portions of the secondthermal medium branch pipes and allows the second thermal medium to flowtherethrough; a second upper reservoir that communicates with the secondheader, and stores the second thermal medium; and a second outlet thatcommunicates with the second upper reservoir and allows the secondthermal medium to flow therethrough, wherein the thermal storagematerial is provided on the outer peripheries of the second thermalmedium branch pipes, and the second upper reservoir is formed in adirection intersecting with a direction of streamline of the secondoutlet, while the first upper reservoir and the second upper reservoirare in contact with each other.
 6. The thermal storage device accordingto claim 5, wherein the first header and the second header are incontact with each other.
 7. The thermal storage device according toclaim 1, further comprising: a plurality of first plate-like tubes thatare arranged in parallel with each other to extend in a verticaldirection of the thermal storage device, wherein the first thermalmedium branch pipes are disposed in the vertical direction of the firstplate-like tubes.
 8. The thermal storage device according to claim 5,further comprising: a plurality of second plate-like tubes that arearranged In parallel with each other to extend in a vertical directionof the thermal storage device, wherein the second thermal medium branchpipes are disposed in a vertical direction of the second plate-liketubes.
 9. The thermal storage device according to claim 8, furthercomprising: a plurality of first plate-like tubes that are arranged inparallel with each other to extend in the vertical direction of thethermal storage device, wherein the first thermal medium branch pipesare disposed in a vertical direction of the first plate-like tubes, andthe first plate-like tubes and the second plate-like tubes are arrangedin parallel with each other so as to be perpendicular to aninlet/outlet-side side face of the thermal storage device in which thefirst inlet and the second outlet are provided.
 10. The thermal storagedevice according to claim 9, wherein each of the first plate-like tubesand the second plate-like tubes is formed by joining two heat transferplates to each other; and the first thermal medium branch pipes and thesecond thermal medium branch pipes are inserted through grooves formedin mating faces of the two heat transfer plates.
 11. The thermal storagedevice according to claim 9, further comprising: a second footer thatcommunicates with lower portions of the second thermal medium branchpipes and allows the second thermal medium to flow therethrough; asecond lower reservoir that communicates with the second footer, andstores the second thermal medium; wherein the first plate-like tubesextend through at least one of the second upper reservoir and the secondlower reservoir, and at least one hole is formed in the first plate-liketubes.
 12. The thermal storage device according to claim 9, furthercomprising: a second footer that communicates with lower portions of thesecond thermal medium branch pipes and allows the second thermal mediumto flow therethrough; a second lower reservoir that communicates withthe second footer, and stores the second thermal medium; wherein thesecond plate-like tubes extend through at least one of the second upperreservoir and the second lower reservoir, and at least one hole isformed in the second plate-like tubes.
 13. The thermal storage deviceaccording to claim 11, wherein the second plate-like tubes extendthrough at least one of the second upper reservoir and the second lowerreservoir, and at least one hole is formed in the second plate-liketubes.
 14. The thermal storage device according to claim 1, wherein thefirst thermal medium comprises brine, and the second thermal mediumcomprises a coolant.
 15. A circulation system comprising: the thermalstorage device according to claim 1; and a heat exchanger, wherein thefirst thermal medium circulates between the thermal storage device andthe heat exchanger.
 16. The circulation system according to claim 15,further comprising: a compressor; a condenser; a receiver tank; and anexpansion valve, wherein the second thermal medium circulates betweenthe thermal storage device and the compressor, and the condenser, thereceiver tank and the expansion valve are connected in the order ofdescription between the compressor and the thermal storage device. 17.The thermal storage device according to claim 2, wherein the first upperreservoir has a bottom face that is inclined upwards from a lowerportion of the upper reservoir.
 18. The thermal storage device accordingto claim 2, further comprising: a plurality of second thermal mediumbranch pipes through which a second thermal medium flows; a secondheader that communicates with upper portions of the second thermalmedium branch pipes and allows the second thermal medium to flowtherethrough; a second upper reservoir that communicates with the secondheader, and stores the second thermal medium; and a second outlet thatcommunicates with the second upper reservoir and allows the secondthermal medium to flow therethrough, wherein the thermal storagematerial is provided on the outer peripheries of the second thermalmedium branch pipes, and the second upper reservoir is formed in adirection intersecting with a direction of streamline of the secondoutlet, while the first upper reservoir and the second upper reservoirare in contact with each other.
 19. The thermal storage device accordingto claim 2, further comprising: a plurality of first plate-like tubesthat are arranged in parallel with each other to extend in a verticaldirection of the thermal storage device, wherein the first thermalmedium branch pipes are disposed in the vertical direction of the firstplate-like tubes.
 20. The thermal storage device according to claim 2,wherein the first thermal medium comprises brine, and the second thermalmedium comprises a coolant.
 21. A circulation system comprising: thethermal storage device according to claim 2; and a heat exchanger,wherein the first thermal medium circulates between the thermal storagedevice and the heat exchanger.